Identification of a novel linear B-cell epitope recognized by a monoclonal antibody against the capsid protein of goose astrovirus genotypes 2.

Abstract

BACKGROUND: Goose astrovirus genotype 2 (GoAstV-2) is a novel and highly infectious pathogen characterized by symptoms of gout, swelling, and hemorrhage of the kidneys in 5-15-day-old goslings. The virus has caused severe economic losses for the goose husbandry industry. The capsid protein of GoAstV-2 is involved in viral packaging and immunogenicity, and it has served as a target antigen for diagnostic methods. RESULTS: In this study, the N-terminus of the GoAstV-2 Cap protein (rCap) was successfully expressed and used to immunize BALB/c mice. A new monoclonal antibody (mAb) named 7B2 against the GoAstV-2 rCap protein was prepared. Immunofluorescence assay and Western blot analysis showed that mAb 7B2 had a strong binding affinity to the GoAstV-2 rCap protein. The results of epitope mapping demonstrated that the minimum linear epitope recognized by mAb 7B2 was located in the amino acidsNTAGPESIDT. Sequence homology analysis revealed that this epitope was highly conserved among the GoAstV-2 strains analyzed and that it showed 90% sequence similarity with turkey astrovirus 2 strains and low similarity (less than 50%) with other astroviruses. CONCLUSIONS: These findings will be useful for the development of diagnostic kits for GoAstV-2 and will aid further research on the structure and function of the capsid protein.